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Biomedical subjects

R C Gallo

Publications and source records attributed to R C Gallo.

At least 253 records · Page 14Linked to original sources
PubMed1988

Antigenic peptides recognized by T lymphocytes from AIDS viral envelope-immune humans.

T-lymphocyte immunity is likely to be an important component of the immune defence against the AIDS virus, because helper T cells are necessary for the antibody response as well as the cytotoxic response. We have previously predicted two antigenic sites of the viral envelope protein gp120 likely to be recognized by T lymphocytes, based on their ability to fold as amphipathic helices, and have demonstrated that these are recognized by T cells of mice immunized with gp120 (ref. 1). A peptide corresponding to one of these sites can also be induce immunity in mice to the whole gp120 protein. Because many clinically healthy seropositive blood donors have already lost their T-cell proliferative response to specific antigen, we tested the response to these synthetic peptides of lymphocytes from 14 healthy human volunteers who had been immunized with a recombinant vaccinia virus containing the AIDS viral envelope gene and boosted with a recombinant fragment. Eight of the 14 responded to one peptide, and four to the other peptide, not included in the boost. These antigenic sites recognized by human T cells may be useful components of a vaccine against AIDS. We also found a correlation between boosting with antigen-antibody complexes (compared to free antigen) and higher stimulation indices, suggesting a more effective method of immunization.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Biologically diverse molecular variants within a single HIV-1 isolate.

AIDS is a disorder characterized by a slow progressive impairment of immune function and by infection of human immunodeficiency viruses (HIV-1, HIV-2). Our knowledge of how these viruses cause disease in man, or how the related lentiviruses (visna and equine infectious anaemia virus) cause disease in animals, is still fragmentary. In particular, the significance of genetic variation in HIV-1, occurring within populations, within individuals and over periods of time, and the mechanisms of viral persistence remain unclear. To address these issues we prepared a series of proviral clones of HIV-1 originating from a single patient and compared their biological properties. Here we show that hybrid genomes (in which the envelope region of six viral clones were separately substituted into a prototype HIV-1 genome) generated viruses with widely differing capacity to grow in human T cells, cell lines and monocytoid cultures. These data suggest that extensive biological variation exists in vivo within an infected individual and is in part determined at the level of the viral envelope.

Acquired Immunodeficiency Syndrome↗
PubMed1988

HIV causes AIDS.

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Acquired Immunodeficiency Syndrome↗
PubMed1988

Geographic distribution of HTLV-I and identification of a new high-risk population.

Epidemiologic studies indicate that human T-cell lymphotropic virus type I (HTLV-I), the causative agent of most cases of adult T-cell leukemia/lymphoma (ATLL) in Southeast Japan and the Caribbean islands and the probable cause of a progressive neurological disorder often referred to as tropical spastic paraparesis, occurs with unusual geographic clustering. The current large-scale serosurvey was undertaken to improve our understanding of HTLV-I prevalence in different parts of the world. We analyzed 43,445 serum samples collected from various geographic locales worldwide; 76% of these sera came from clinically healthy donors. Samples were initially screened by an enzyme-linked immunosorbent assay (ELISA) and 4,353 were further evaluated by means of competition assays. In this study, which did not include sera from endemic areas of Japan, a high prevalence of infection was observed in several countries in the Caribbean basin. A significant age-sex difference was observed between populations in the Caribbean and non-endemic regions of Japan. The reason for the male excess in non-endemic areas of Japan will require further study, while the female excess in the Caribbean basin is compatible with the previously described pattern for other HTLV-I-endemic areas. A newly recognized area of possible endemicity was southern Florida, where evidence of infection with HTLV-I or a related virus was found in a group of native Americans whose sera were collected in 1968. In certain parts of the world, particularly sub-Saharan Africa, important problems in determining specificity of reactivity occurred, probably because of cross-reacting antibodies. No pattern was detected that could explain the cross-reactivity solely on the basis of geographic areas, specific patterns of non-viral parasitic infection, or methods of handling the specimens. It is possible that these cross-reactivities are antibodies to proteins from HTLV-I-related retroviruses yet to be discovered.

Adult↗
PubMed1988

Type-restricted neutralization of molecular clones of human immunodeficiency virus.

In a study of the immunologic significance of the genetic diversity present within single isolates of human immunodeficiency virus type 1 (HIV-1), the neutralization of viruses derived from molecular clones of the HIV-1 strain HTLV-IIIB by an extensive panel of sera was compared. Sera from HIV-1-infected patients and from goats immunized with polyacrylamide gel-purified HIV-1 envelope glycoprotein (gp120), native gp120, or gp120-derived recombinant peptides, showed marked heterogeneity in neutralizing activity against these closely related viruses. The change of a single amino acid residue in gp120 may account for such "clonal restriction" of neutralizing activity.

Amino Acid Sequence↗
PubMed1988

Generation of a neutralization-resistant variant of HIV-1 is due to selection for a point mutation in the envelope gene.

Transmission and growth of HIV-1 produced from the biologically active clone HTLV-III/HXB2D in the constant presence of a neutralizing antiserum yielded a viral population specifically resistant to neutralization by the same antiserum. Molecular clones MX-1 and -2, containing the entire envelope gene, were obtained from cultures of the resistant variant. The coding regions for the large envelope protein and most of the transmembrane envelope protein of two such clones were substituted for the homologous segment of HXB2D. Infectious viruses from these constructs were also specifically resistant to neutralization by the selecting antiserum. The exchanged fragment contained only one base change, resulting in an Ala----Thr replacement at position 582. When this substitution was introduced into HXB2D it conferred the resistant phenotype. Thus, small differences may be selected for in vivo by the host immune response and result in relatively large differences in susceptibility of the virus to such a response.

Antibodies, Viral↗
PubMed1988

In vitro cellular tropism of human B-lymphotropic virus (human herpesvirus-6).

We investigated the cellular tropism of human B-lymphotropic virus (HBLV) (also designated Human Herpesvirus-6) in vitro by infecting fresh MN cells from normal human adult peripheral blood, umbilical cord blood, bone marrow, tonsil, and thymus. Cultures from all the sources examined contained infectable cells, as shown by the appearance of characteristic enlarged, round-shaped, short-lived cells expressing HBLV-specific markers. Detailed immunological analysis demonstrated that the vast majority of these cells expressed T cell-associated antigens (i.e., CD7, CD5, CD2, CD4, and to a lesser extent, CD8). The CD3 antigen and the TCR-alpha/beta heterodimer were not detectable on the surface membrane, but were identified within the cytoplasm of HBLV-infected cells, by both immunofluorescence and radioimmunoprecipitation assay. A proportion of the HBLV-infected cell population also expressed the CD15 and class II MHC DR antigens. By means of immunoselection procedures it was possible to show that a consistent proportion of HBLV-infectable cells were contained within the CD3-depleted immature T cell population, while the depletion of CD2+ cells completely abrogated the infectability of the cultures. Northern blot analysis confirmed the T cell origin of HBLV-infected cells, demonstrating the expression of full size TCR-alpha and -beta chain mRNA. In addition to fresh T cells, HBLV was able to infect normal T lymphocytes expanded in vitro with IL-2 for greater than 30 d. These results indicate that HBLV is selectively T cell tropic in the course of the in vitro infection of normal mononuclear cells and may therefore be directly involved in the pathogenesis of T cell related hematological disorders. In particular, in light of the cytopathic effect exerted in vitro on CD4+ T lymphocytes, a possible role of HBLV in immune deficiency conditions should be considered.

Adult↗
PubMed1988

Molecular epidemiology of HTLV-I-associated non-Hodgkin's lymphomas in Jamaica.

As part of epidemiologic studies of human T-lymphotropic virus (HTLV)-I-associated malignancies in Jamaica, the authors evaluated 26 patients with non-Hodgkin's lymphoma for the presence of integrated HTLV-I provirus in their malignant cells. Fifteen of 26 patients had integrated provirus. All 15 also were HTLV-I antibody positive. Eleven patients did not have integrated provirus, and all 11 were antibody negative. All of the antibody-positive cases had onset of their disease in adulthood (age range, 21-57 years) as opposed to the broad age range of negative cases (4-66 years). Clinical features which were more common in provirus positive than negative patients included leukemic phase, skin involvement, and hypercalcemia, which are all features frequently seen in HTLV-I-associated adult T-cell leukemia/lymphoma (ATLL). The presence of skin involvement, circulating malignant cells, abnormal liver function tests, or the presence of two or more of these four features were statistically significantly different between virus-positive and virus-negative cases. Although the survival of positive cases (6 months) was shorter than that of negative cases (9 months), this was not statistically significant. The only significant determinant of survival was hypercalcemia, with those who developed hypercalcemia at some point in their disease course, independent of their HTLV-I status, surviving a mean of 5 months as compared to a mean of 17.5 months in those who never became hypercalcemic. The six HTLV-I-positive lymphomas that underwent cell typing were all primarily OKT4 positive, whereas two HTLV-I antibody-negative cases that were typed were B-cell lymphomas.

Antibodies, Viral↗
PubMed1988

Envelope sequences of two new United States HIV-1 isolates.

One of the striking molecular aspects of the human T-cell lymphotropic virus type III (HTLV-III) (now called HIV-1) is an unusually large variability in the env genes of different isolates. These differences are clustered primarily within the coding sequences for the large envelope protein and are interspersed among regions within the env gene of relative constancy. Differences among the envelopes of isolates from Africa are so far greater than those among U.S. isolates, but few U.S. isolates have been characterized to date. We report the sequence of the env gene of two U.S. isolates [HTLV-III(MN) and (SC)] and compare them with previously characterized isolates. These two isolates differ substantially from all previously described isolates, especially in the region coding for the large envelope proteins. The env genes of the two new HIV-1 isolates contain conserved and hypervariable regions similar to what has been reported for other isolates, helping to further define those regions. A comparison of the envelope sequences of all the U.S. isolates shows that the similarity between any two ranges from 81 to 85% [except for LAV(BRU) and HTLV-III(BH10) which are 97% similar]. Similar analyses of the African (Zairean) isolates give significantly lower values [71 to 78%, except for 88% between LAV(ELI) and Z6]. This suggests that the African isolates diverged earlier than the U.S. isolates or that transmission of the virus has been more rapid in Africa. Two previous presumptive Haitian isolates are similar to each other and to the U.S. isolates to the same degree as are other U.S. isolates, but differ more markedly from the African isolates suggesting a common lineage of Haitian and U.S. HIV-1 isolates.

Amino Acid Sequence↗
PubMed1988

Antibody prevalence to HBLV (human herpesvirus-6, HHV-6) and suggestive pathogenicity in the general population and in patients with immune deficiency syndromes.

Detailed serologic screening showed an antibody prevalence to HBLV (HHV-6) in the general population of 26% if very strict criteria for antibody positivity were applied. Lower and borderline antibody titers yet may be found in up to 63% of the population. Only 17% of these persons have clinical symptoms; in the majority infection remains silent. HHV-6 infection apparently occurs already quite early in life, and initial symptoms can occur, such as short-term high fever, sore throat, local lymphadenopathy and skin rash. Lesions disappear without specific treatment. The frequency of positive antibody tests at higher titers rises in patients with immune deficiency and with atypical lymphoproliferative diseases to 60 and 75%. The rise in antibody titers is associated in patients with immune deficiency by characteristic shifts of blood lymphocyte populations, essentially by increase in immature T-lymphocytes. Highest titers are found in patients with lymphoproliferative syndromes, yet the percentage of atypical lymphoid cells harboring the viral genome is low (about 2% of seropositive patients). Thus it appears, that HBLV, similar to other herpesviruses such as Epstein-Barr virus, usually causes a silent seroconversion, yet may be associated with variable clinical pathology when persisting in an active state. Its pathogenic effect might be rather a cofactor contributing to immune disturbance than overt oncogenicity.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Molecular studies of HHV-6.

Methods for the purification of enveloped HHV-6 virions and the viral DNA are presented. The viral genome is estimated to be 170,000 base pairs in size and does not appear to contain inversions due to absence of submolar bands by restriction enzyme analyses. The genomes of two independent HHV-6 isolates, HHV-6GS and HHV-6Z29, showed restriction enzyme site pleomorphism. Large scale purification of enveloped HHV-6 was achieved by continuous flow centrifugation utilizing sucrose gradients, DNAse 1 treatment and banding on 10-30% Dextran T10 gradients. The viral proteins were visualized on high resolution two dimensional polyacrylamide gels and the proteins recognized by serum antibody from patient GS were detected by HR2D Western blot analysis and radioimmunoprecipitation assay. The major antigenic proteins were 200, 120, 80, 72, 30 and 19 kDa.

Blotting, Western↗
PubMed1988

Polymerase chain reaction amplification and in situ hybridization for the detection of human B-lymphotropic virus.

Polymerase chain reaction amplification (PCR) is a recently described technique that allows for the amplification of a given sequence of DNA. It can be used to reliably amplify sequences of up to 3 kb within hours. The amplified sequence can then be recognized by hybridization with a specific probe after transfer onto nitrocellulose or nylon paper. We used PCR to recognize human B-lymphotropic virus (HBLV or HHV-6) specific sequences in various tumors as well as in the blood of patients with AIDS. Sixty-three specimens of DNA extracted from peripheral blood of patients with AIDS as well as DNA extracted from various lymphoproliferative disorders were analysed; 52 out of 63 (83%) patients with AIDS were found to have amplification of the HHV-6 specific sequence; 2 out of the 63 (3%) had equivocal amplification and 9 (14%) were found to be negative. Twenty out of 23 tumors were found to have amplified HBLV-specific sequences. Only one of these tumors was positive by Southern hybridization on restriction enzyme digested genomic DNA. In situ hybridization of clinical specimens using radiolabelled RNA probes or hapten-labelled DNA probes was used to detect the presence of HBLV in tumors. Three tumors of B cell origin were found to be positive for HBLV.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Cytopathic effect of human immunodeficiency virus in T4 cells is linked to the last stage of virus infection.

A principal feature of acquired immunodeficiency syndrome is depletion of T4 lymphocytes, which is partly due to a direct cytopathic effect of the virus. Both syncytial formation (viral-induced cell fusion) and premature cell death have been cited as the major cause for this phenomenon. By kinetic analysis of cell proliferation and cell lysis we show that the cytopathic effect correlates chiefly with virus production from infected cells, including giant syncytial cells. Most T4 cells were, at least transiently, infected by human immunodeficiency virus (human T-lymphotropic virus type IIIB strain); however, after phytohemagglutinin activation, only 10-30% of infected cells express virus (and die) at any one time, indicating that virus production, followed by cell killing, is linked to immune activation and cell differentiation. We also show that an interval exists before viral release, in which expression of viral antigens occurs on the cell surface, suggesting that infected cells are immunogenic before viral production. If so, they may induce a cell-mediated immune response that could minimize dissemination of human immunodeficiency virus, a possibility that has influenced our approaches to the development of a vaccine for prevention of acquired immunodeficiency syndrome.

Cell Line↗
PubMed1988

Monoclonal antibodies against human immunodeficiency virus (HIV) type 2 core proteins: cross-reactivity with HIV type 1 and simian immunodeficiency virus.

Four mouse monoclonal antibodies were developed after immunization with one human immunodeficiency virus (HIV) type 2 isolate and were tested for reactivity with different HIV-1, HIV-2, and simian immunodeficiency virus (SIV) isolates in an immunofluorescence assay and by immunological blot analysis. One of them, an anti-capsid (p24) antibody, called R1C7, reacted with all HIV-1, HIV-2, and SIV isolates tested, thus identifying an epitope shared by all HIV and SIV. Another anti-capsid antibody, named A4F6, reacted with three HIV-2 isolates (HIV-2NIH-Z, LAV-2Rod, and LK001 ST9), some SIV isolates (STLV-IIIAGM, SIV-251, and SIV-309), but no HIV-1 isolates. Two anti-matrix (p16) antibodies, named R5C4 and R5F6, reacted strongly only with the HIV-2 isolates. The use of these monoclonal antibodies for rapid discrimination and identification of acquired immunodeficiency syndrome-related retroviruses is discussed.

Animals↗
PubMed1988

Processing of the structural proteins of human immunodeficiency virus type 1 in the presence of monensin and cerulenin.

The synthesis and processing of structural proteins of human immunodeficiency virus type 1 (HIV-1) were studied in infected cells treated with monensin and cerulenin. In MOLT-3 cells chronically infected with HTLV-IIIB, monensin inhibited the proteolytic cleavage of the env-coded polyprotein gp160 to gp120, leading to the accumulation of the precursor gp160. The formation of syncytia normally observed when CEM cells are cocultivated with HIV-1-infected MOLT-3 cells was significantly inhibited in the presence of monensin. The effect of the ionophore on the culture was reversible, as withdrawal of monensin from the medium restored the ability of the cells to form syncytia with CEM cells and led to the resumption of the processing of gp160 to gp120. Monensin did not affect the synthesis and processing of gag-coded proteins and regulatory proteins. Cerulenin, an inhibitor of de novo fatty acid biosynthesis, inhibited the myristoylation and the proteolytic cleavage of the gag-coded polyprotein Pr53gag to p24 but did not affect the processing of gp160. However, use for monensin and cerulenin as antiviral agents for treatment of HIV-1 infection cannot be foreseen because of the pronounced in vitro toxicity observed.

Antifungal Agents↗